Luminescent transfer paper



Unite LUMINESCENT TRANSFER PAPER Application April 29, 1955, Serial No. 504,938

6 Claims. (Cl. 117-335) This invention relates to a carbon paper, carbon ribbon, fabric ribbon, or other copying or marking element such as crayon or chalk, or the like, and has for its object to afford a copying or marking structure that is capable of producing a secret mark or record which is invisible or partially visible normally or in ordinary light, and which fluoresces and becomes visible or more visible when exposed to ultraviolet light or to some form of radiating energy.

A more particular purpose is to provide a carbon paper with a copying surface or coating which when exposed to ultraviolet light or other radiation fluoresces and re-emits a different color or light wave length from that to which it is exposed, thus enabling a mark or record that is invisible in ordinary or normal light to become visible when exposed to ultraviolet light or to other selected wave lengths of electro-magnetic radiation, or when subjected to such energy stimulations as those produced by magnetic fields, sonic and ultrasonic agitations and the like.

A further objective is to provide a paper with a copying layer including an organic or inorganic luminescent substance or material for making normally invisible or secret records, such for instance as orders, directions, or communications to air pilots which can be read in the cockpit of a plane when exposed to ultraviolet light.

An additional purpose is to produce a carbon or copying paper having on its under surface a carbon coating that is transferred to the top surface of an underlying copy sheet, and on its top surface a copying coating including a luminescent substance or material that produces on the under surface of an overlying record sheet a negative or reverse copy which is invisible in ordinary light and which becomes visible when exposed to ultraviolet light or other selected methods of activation, or energy. This enables producing a conventional carbon copy of typewritten matter on an underlying copy sheet, and a reverse or negative normally invisible copy on the under surface of an overlying record sheet on which the matter is typewritten, thus retaining an invisible or secret copy of the matter in question which can be referred to in case the carbon copy is erased or obliterated.

A further object is to provide a carbon paper such that when a series of such carbon sheets are interleaved between a series of sheets of copy paper, and matter is typewritten on the top or record sheet of paper, a carbon copy of the typewritten matter is transferred to the top surface of each underlying sheet of copy paper, and a substantially invisible negative or reverse copy of the typewritten matter is transferred to the under surface of the top sheet of record paper, and of each sheet of copy paper, except the lowermost sheet, such reverse copies being invisible in ordinary light and visible when exposed to ultraviolet light or to other radiating energy having a wave length different from the wave length that is re-emitted from the copy, so that as erasures are made on a carbon copy, the normally invisible negative Yor *rates arent' ICC reverse copy remains on the under surface of the record and copy sheets and can be read under ultraviolet llght.

An additional purpose is to provide a carbon paper or other marking element that will produce on a paper sheet an invisible record which fluoresces and can be read when subjected to the proper selective light or energy wave length, and contains a luminescent substance that can be applied to or embodied in carbon paper, carbon ribbons, fabric ribbons, crayons, chalk, and other applications where normal invisibility and secrecy is important.

Another object is to provide on a paper support a carbon coating layer containing therewithin or coated thereover a luminescent substance which protects the carbon layer and results in a more or less permanent and determinable record when subjected to ultraviolet light or other radiation of energy, in the event that the carbon record is partially obliterated.

A further purpose is to afford a paper support coated with a layer of wax and oil containing or having applied to its surface a luminescent material which enables making a record that is normally invisible and which fluoresces and becomes visible when exposed to energy or radiation of a selected wave length.

Another purpose is to produce a carbon paper having a carbon coating containing a luminescent substance which gives a more legible and clearer copy, and which is less subject to erasure than a conventional carbon coating layer, and it is also within the province of the invention to atford a carbon paper support with various selected coatings capable of being rendered uorescent by magnetic fields alone, or in conjunction with activation by electromagnetic radiations.

To these and other ends, the invention consists in the construction that will appear clearly from the following description when read in conjunction with the accompanying drawings, the novel features being pointed out in the claims following the specilication.

In the drawings:

Fig. l is a diagrammatic sectional view illustrating one embodiment of the invention comprising a paper support coated with a luminescent copying layer, and illustrating sheets of record and copy paper above and below the carbon paper;

Fig. 2 is a similar view illustrating the invention as applied to a carbon paper in which one surface is coated with a luminescent copying layer and the reverse surface is coated with a conventional carbon copying layer;

Fig. 3 is a similar view illustrative of the invention as applied to a carbon paper in which one surface of the paper support is coated with a conventional carbon copying layer and the carbon copying layer is coated with a luminescent layer;

Fig. 4 is a similar view in which a paper support is provided on one surface with a luminescent copying layer and on its reverse surface with a conventional carbon copying layer which in turn is coated with a luminescent copying layer, and

Fig. 5 is a similar View in which a paper support is coated on one surface with a wax layer and the wax layer in turn coated with a luminescent layer.

Referring more particularly to the drawings in which like reference numerals refer to the same parts throughout the several views, and to Fig. 1, ll designates a tissue paper or other support which is coated with a luminescent copying layer 2, while 3 `designates a sheet of record paper which is positioned against the top surface of the support 1 to receive typewriting, and 4 designates a sheet of copy paper that is positioned against the bottom surface of the luminescent copying layer 2 and receives therefrom a copy of the matter that is typewritten upon the top surface of the record layer 3. The luminescent layer may be visible or substantially white or invisible and formed from organic or inorganic materials or combinations thereof, as

will be described hereinafter.

The matter transferred to or recorded on the surface of the copy paper 4 Ymay be partially visible or invisible in normal or ordinary light land luoresces tto-become visible when exposed to ultraviolet light or other energy having a diiferent wave lengthA from that which is re-'emitted from the luminescent copy on the copy paper 4, so that the matter recorded thereon is of a secret or invisible nature. and readable only when exposed to `the `proper lselected activation.

In Fig. 2, the paper support 1 has a 4conventional carbon copying layer 5 applied to its under :surface and a luminescent copying layer-6 coated upon` its upper surface, and in the use of such a copying element, when the record land copy sheets are in contact with the copying element and typewritten matter is applied tothe top surface 'of the record sheet Y3, a conventional'carboncopy isproduced-Son the top surface of the copy paper 4, and a normally visible reverse or negative copy isproduced onthe under surface of the record sheet 3, thus affording a permanent secret record on the under surface of the record sheet 3 ofthe matter that is typewritten on the top surface of the Irecord sheet and transferred bythe carbon layer4 tothe top surface of the copy sheet 4.

With this arrangement, by interleaving a series of the copy elements -between a multiplicity of sheets of 'copy paper,the top or record sheet and all the copy sheets will have anvinvisible copy on their under surfaces in negative or reverse, capable of being read under ultraviolet light or other selected activation ditferent in type or wave length from that'of the energy re-emitted from the luminescent record, `and each sheet of copy will have on its upper surface the usual carbon copy. If a carbon copy is erased or obliterated, recourse can always be had to the permanent invisible records on the reverse surfaces of the'rec'ord or copy sheets.

The term luminescent where used throughout this application isintended to include and denote both fluorescent materials, which are activated by energy of shorter wave length and re-emit energy of longer wave length, and phosphorescent materials which continue to re-emit light or energy after excitation is discontinued, and the invention includes any luminescent, fluorescent, or'phosphorescent materials, either organic orinorganic, or any materials which are partially visible or substantially invisible, Vin' normal or ordinarylight, and whic'hbecorne visible'orreemit energy when exposed lto light or energy differing in kind or wave length from that remitted by the luminescent substance.

In the use of such materials for carbonpaper, asuitable mix consists of carnaubawax and pharmaceutical grade mineral oil, with which isrnixed zinc sulfide phosphor or other substances treatedltoproduce luminescence. The complete mix consists of approximately 32% 'carnauba wax, 21% mineral oil,1an'd approximately 47% ofpigment or zinc sulfide component.

`Where zinc `sulfide is employed, a pure zinc sulfide is ground in a porcelain ball/mill with an anionic or cationic impurity, or activator, such as gold which 'produces a slightly yellow color, inthe concentration 'of one part of gold in tenthousand parts of zinc sulfide, and heated to approximately 1050 C., to forma crystal structure. A greater or less proportion of gold may be used and in place of gold for combining with zinc sulfide, other suitable activators may be employed, such in general as copper, silver, bismuth, or manganese in the same concentration as gold, depending upon the particular color that is tobe imparted to the luminescent substance.

The luminescent substance/may be incorporatedin va conventional carbon coating layeror it may be applied Aas a coating 7 over the conventionall carbon copying. layers as illustrated in Fig. 3, in which instance theluminescent record is imposed on the copy sheet 4, and the carbon record overlies the luminescentrrecord so that if the carbon record is erased, the luminescent substance adheres to the copy paper 4, and serves as a secret record of the typewritten matter which is visible only when exposed to ultraviolet light or other source of activation or energy.

Where the luminescent layer is applied to a paper support, the luminescent activator may ,beincorporated in the wax mixture and applied to the paper support as in Fig. l, or ,a wax coating consisting for instance of carnauba wax and mineral oil may =be applied to the papersupport and the luminescent substance dusted over or otherwise applied to the surface of the wax layer, and where an element Asuch Yas disclosed in Fig. 1 is used, it may be ernployed to produce an invisible copy or record on the underlying copy sheet, or itmay be reversed and employed with the luminescent layer against the under surface of the record sheet, thus operating to produce an invisible reverse or negative record on the under surface ofthe `record sheet 3.

Fig. 4-shows a luminescent layer 6coated on the upper surface of apaper support 1, with a carbon layer 5 coated on the under surface of the support 1, and a luminescent layer 8 over the carbon layer, resulting in a luminescent carbonrecord onfthe upper surface ofthe copy sheet and an invisible'reverse copy on Vthe under surface of the record sheet, and Fig. 5 shows a paper support 1 having -a wax layer 9'applied to its undersurface, and a luminescent coating ltlfcovering'the outer surface of the wax layer 9, the luminescent -substance being `dusted or otherwise affixed on the waxlayer.

Instead of zinc sulfide phosphor for the luminescent substance, any suitable dyes or other substances, organic or inorganic, may 'be-employed that have the characteristic 0f fluorescing'when exposed to energy, such as sound lor light waves, :or'felectromagnetic 'rays of different wave length fromthat which the luminescent material re-emits.

The luminescent coating layer may be Ano either or both surfaces lof a paper support and may be either visible in ordinary light or substantially invisible or white in ordinary light, and when'the coating is more or less visible, it is sharper, becomes more legible when subjected to certain'energy wave lengths, and affords additional protection to a carbon impression and a permanentrecord-Ii'f the carbon is-erased.

Whilethe inventionhas been described with reference to `certain embodiments-it is not restriced to the particular `details herein -set forth, and this lapplication is intendedrto cover `such changes or 4modifications as may come :within the -intent of the improvements and the scope of thefollowing claims.

.1. As *an l. article of manufacture, a paper support having coated directly thereon a readily transferrable mixture `containing wax and'a'luminescent substance, which luminescent substance is substantially invisible in ordinary lightfanduoresces'when exposed to energy having a lwave length different from that re-emitted 'by the luminescent substance.

2. As an article'of'manufacture, a paper support having v'directly 'thereon lareadily transferrable coating of wax carrying oniits surface a luminescent substance which is substantially invisible in ordinary light and uoresces whentexposed to energy 'having a wave length different from f that i re-emitted vby the' luminescent substance.

3. A 'transfer y'element 'comprising Va paper support coated directlywith a readilytransferrable copying layer containing -wax -and 'a "luminescent substance which is substantially invisible in ordinary Vlight and iiuoresces wheniexposed "to energy having awave length different from' thatfre-emittedtby the luminescent substance.

'4. LA transfer element comprising a paper support coated-ffdirectly-"onfone'surface with acarbon .copying layeriand 'directly onfits' reverse surface `with a readily :transfer-table copying layervcontainingwax and a luminescent subst-ance which is substantially invisible in ordinary light and which fluoresces when exposed to energy having a wave length different from that re-emitted by the fluorescent substance.

5. A transfer element comprising a paper support coated directly with a readily transferrable copying layer containing wax and oil and having an exposed surface of luminescent substance which 'is substantially invisible in ordinary light and which tluoresces when exposed to energy having a wave length diierent from that reemitted by the luminescent substance.

6. A transfer element comprising a paper support coated directly on one surface with -a readily transferrable copying layer containing wax, oil, and a pigment, and coated directly on its reverse surface with a copying layer containing wax, oil, and a luminescent substance which is substantially invisible in ordinary light and which tluoresces when exposed to energy having a wave length different from that re-emirtted by the luminescent substance.

References Cited in the le of this patent UNITED STATES PATENTS 2,146,515 Schmidt Feb. 7, 1939 2,372,209 Kohler Mar. 27, 1945 2,710,285 Trusler June 7, 1955 

1. AS AN ARTICLE OF MANUFACTURE, A PAPER SUPPORT HAVING COATED DIRECTLY THEREON A READILY TRANSFERRABLE MIXTURE CONTAINING WAX AND A LUMINESCENT SUBSTANCE, WHICH LUMINESCENT SUBSTANCE IS SUBSTANTIALLY INVISIBLE IN ORDINARY LIGHT AND FLUORESCES WHEN EXPOSED TO ENERGY HAVING 